Preparation of asphalt



Patented Nov. 14, 1939 UNlTED sTATEs PATENT oFFies to The Standard Oil Company,

Cleveland,

Ohio, a corporation of Ohio No Drawing. Application November 22, 1937, Serial No. 175,773

3 Claims.

Asphalt products, particularly in roofing and paints incur extremely drastic usage conditions in the extended exposure in sunlight and air and have a tendency to cracking and checking. In accordance with the present invention however asphalt may be prepared giving remarkable durability in such usages.

To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described, and particularly pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative however,'of but a few of the various ways in which the principle of the invention may be employed.

In accordance with the invention, a residuum of asphalt-furnishing character, preferably from pipe still bottoms, for instance as from Mid-Continent stock, and with a proportion of cylinder stock, is first subjected to oxidation, as by airblowing. The pipe still bottoms may be in amount of '75 to 85 per cent, and the cylinder stock 15 to 25 per cent. The oxidation is carried on until the material, on sampling shows a softening point of 20 to F. below the desired final specification softening point, and then aluminum chloride is introduced in relatively small amount. The temperature of the oxidation airblowing operation may in general be 400 to 550 F. And in the further treatment with aluminum chloride, the temperature is maintained generally, as for instance 300 to 450 F. The amount of aluminum chloride introduced may be 0.1 to 1.0 per cent or slightly more. Generally, less than one per cent is advantageous.

As an example: Pipe still bottoms from Mid- Continent petroleum, in amount of seventy-five per cent, and cylinder stock in amount of twentyfive per cent, is air-blown at a temperature of 500 F., until the material shows a softening point of about 166 F., and 3'7 penetration at 77 F. Aluminum chloride is then added in amount of 0.25 per cent by weight, and with the temperature maintained at about 360 F., and thorough stirring, action proceeds without air feed, until sampling shows a softening point of about 201 F. and 30 penetration at 77 F. 5

Asphalt thus prepared shows a remarkable resistance to cracking and checking, in exposure, as in paints, roofings, etc.

Other modes of applying the principle of the invention may be employed, change being made 10 as regards the details described, provided the features stated in any of the following claims, or the equivalent of such, be employed.

I therefore particularly point out and distinctly claim as my invention: l5

1. A process of making asphalt, which comprises oxidizing a mixture of about seventy-five per cent pipe still bottoms and about twenty-five per cent cylinder stock to a softening point of about 166 F. and about 37 penetration at 77 20 F., discontinuing such oxidizing operation and subjecting the material to the action of about onefourth of one per cent of aluminum chloride at a temperature of about 360 F.

2. A process of making asphalt, which com- 25 prises oxidizing a mixture of about seventy-five per cent pipe still bottoms and about twenty-five per cent cylinder stock to a softening point 20 to 50 F. below the desird specification point, discontinuing such oxidizing operation and subject- 30 ing the material to the action of one-tenth to one per cent of aluminum chloride at a temperature of 300 to 450 F.

3. A process of making asphalt, which comprises oxidizing a mixture of asphaltic residuum 35 and cylinder stock, discontinuing such oxidizing operation and subjecting the material to the action of about one-tenth to one percent of aluminum chloride at elevated temperature but not substantially higher than in the oxidizing operation.

CHARLES H. WI-IITACRE. 

